The present invention is related to a polymer molding/processing technique, and more particularly to an airtight mechanism of a mold-holding unit for forming a vacuum environment around a held mold.
Taiwanese Utility Model Patent No. 093219334 discloses a middle heating disc module of a vacuum sulfur-adding machine. Such module utilizes a conventional vacuum chamber technique. Basically, such module includes a vertical mold-holding unit having an upper fixed mold seat. A guide column projects from lower side of the upper fixed mold seat. A vacuum chamber is slidably fitted on the guide column to provide airtight sealing effect for a mold positioned thereunder. An external negative pressure device is used to suck away the gas in the close space defined by the vacuum chamber. Accordingly, a vacuumized space is achieved for the polymer manufacturing/processing procedure.
The conventional technique is widely applied to the manufacturing. However, such structure is still not perfect. Mainly, for the mold-holding unit with the conventional vacuum chamber, it is necessary to reserve a considerable room under the upper fixed mold seat, in which the vacuum chamber can be disposed. Under such circumstance, the mold-holding unit must have a considerable total height. This makes it inconvenient to maintain and operate the mold-holding unit.